A Becton Dickerson FACScan is available in the Department of Microbiology for use by the investigators in this Program. All of the projects require use of analysis by flow cytometry. Funds are requested to provide partial support for the service contract on this instrument and for partial support of a technician who will maintain the instrument and train new users. The data storage capacity of the FACScan system is currently very limited. In order to support data storage and analysis by the multiple users under this program, a peripheral data storage system is requested. Dr. Marc Jenkins will supervise the FACScan laboratory. Funds are also requested for Administrative Assistance for the Program.